In this study, we developed a scale for measuring four sources of career decision-making self-efficacy (CDMSE) among Japanese university students. The study participants were undergraduate students (age range, 18–23 years) from three universities in Japan. We conducted a questionnaire survey during the last 20 minutes of a lecture and obtained complete responses from 270 students. We applied the stages of change theory and the Japanese version of the Career Decision-Making Self-Efficacy Scale to determine motivation toward career decision-making behavior and CDMSE, respectively. To generate items for the CDMSE Source Scale, we conducted four focus group interviews with 26 university students. As a result, we selected 50 items as raw items for the CDMSE Source Scale, which the participants responded to on a four-point Likert-type scale. As a result of exploratory factor analysis, we devised a scale with 29 items arranged into four factors.
